1. Field of the Invention
The invention relates generally to a method for determining an image area to be exposed on a lithographic printing plate, and more particularly, to a method for reducing tolerances and margins of error when determining an imaging area of a lithographic printing plate on a platesetter or imagesetter.
2. Description of the Prior Art
Printing plates are imaged on internal drum, external drum and flatbed imagesetters and platesetters where an image is transferred from an imaging head to the printing plate via a laser beam. Printing plates can be black and white or they can represent color separations, such as cyan, magenta, yellow and black.
A finished printing plate is used on a printing press to transfer ink to a substrate such as paper. The mechanics of the printing press requires that the printing plate must be accurately positioned and aligned on the printing press. This is typically accomplished by aligning and engaging pins on the printing press with slots or notches that have been cut along the non-imaged edges of the printing plate. The positioning of these notches is critical with respect to the edges of the printing plates and the location of the image that is transferred onto the printing plate. Misalignment or variation in the positioning of the image on the printing plate with respect to the edges of the printing plates and the notches along the edges of the printing plates can cause problems in printing an accurate image onto the final print medium (often paper, although the same applies to any known print mediums).
The above problems associated with misalignment or variation in the positioning of the image on the printing plate, with respect to the edges of the printing plates and the notches along the edges of the printing plates, are corrected in view of the current invention as claimed and described in the following description and drawings.